This invention relates generally to watercraft lifts and more particularly concerns the structural components connecting the lift floatation tanks to the watercraft support frame.
In connecting lift floatation tanks to a watercraft support frame, the frame is fixed to the floatation tanks by bolts through flanges on the tanks, by metal belts tautly pulled around the cross-sections of the tanks or by use of welded assemblies of metal tubes and brackets with the tubes fitted into grooves in the sidewalls of the tanks. The bolts, surrounding belts and side mounted tube assemblies are continuously exposed to water. The integrity of the tank is eventually compromised by the reciprocating forces exerted at the bolt holes on the tank plastic while the lift is in use. The connections to the frame are typically located proximate the front and rear ends of the tanks. As a result, the weight of the watercraft is applied to the front and rear ends of the floatation tanks. The buoyancy force of the water, however, is applied to the entire length of the tanks. Therefore, the presence of the watercraft on the lift causes the hollow plastic tanks to bow downwardly at the ends, distorting the watercraft support frame. The use of side-of-tank tube assemblies may reduce the distortion to some extent, but the constant exposure of the metal tubes to the water far outweighs any such benefit. The deflection problem is most often resolved by the use of more plastic in the tank walls than would otherwise be necessary so as to strengthen the resistance of the tanks to deflection. Unfortunately, added plastic means a heavier and more expensive tank. In addition to these unique deficiencies, all of these known connecting systems are troublesome to install.
It is, therefore, an object of this invention to provide an improved watercraft lift. Another object of this invention is to provide a watercraft lift with a connecting assembly which does not use metal components below the waterline of a floatation tank. A further object of this invention is to provide a watercraft lift with a connecting assembly which does not compromise the structural integrity of the floatation tanks. Yet another object of this invention is to provide a watercraft lift with a connecting assembly which does not require the insertion of bolts through the floatation tank plastic. It is also an object of this invention to provide a watercraft lift with a connecting assembly which does not require the use of belts to girt the floatation tanks. Still another object of this invention is to provide a watercraft lift with a connecting assembly which does not require the engagement of welded tube and bracket assemblies in the side walls of the floatation tanks. An additional object of this invention is to provide a watercraft lift with a connecting assembly which does not place unnecessary stress on the floatation tank walls. Another object of this invention is to provide a watercraft lift with a connecting assembly which resists buoyancy-caused deflection of the floatation tanks. A further object of this invention is to provide a watercraft lift with a connecting assembly which enables use of thin-walled plastic floatation tanks. Yet another object of this invention is to provide a lightweight watercraft lift. And it is object of this invention to provide a watercraft lift with a connecting assembly which is easily installed.